A new modified algorithm for elastic-plastic FEM: Quasi-chord modulus method (Q2641147)

The authors propose a new algorithm for elastic plastic finite element analysis, called quasi-chord modulus method (QCM). This method consists in factorizing a quasi-chord stiffness matrix by choosing an ``enlarging factor'' C of the chord modulus \(\bar Ep\), and then a quasi-chord modulus Ec defined as \(\bar Ep\) multplied by the factor C, to modify the elasticity modulus in the stiffness matrix of the initial configuration. With the QCM method, the convergent displacement, strain and stress solutions in each small load step are obtained with fewer iterations than in the methods, and with much less time for the calculation of the stiffness matrix than for the full Newton-Raphson and modified Newton- Raphson methods. Moreover, by the QCM method the nearly incompressible element matrix can be easily obtained and the numerical difficulties caused by the incompressibility condition of Mises materials are efficiently overcome.